Abstract. Grape (Vitis vinifera L.) is a major agricultural crop with significant economic value worldwide, including Azerbaijan. Grapevines in Azerbaijan face significant challenges from downy mildew (Plasmopara viticola), a fungal disease that affects grape yield and quality. This study aimed to evaluate the resistance of 37 grapevine varieties to downy mildew under natural field conditions. The results revealed two main genotype clusters: 13 varieties were classified as tolerant (scoring 3-3.5), while 24 varieties were classified as susceptible (scoring 4-4.5). No varieties were found to be highly resistant or highly susceptible. The evaluation process utilized a 5-point scale to assess disease severity on leaves and clusters. Findings from this study are crucial for identifying grapevine varieties with improved resistance to downy mildew, aiding in the development of more resilient grape cultivars. These results have significant practical implications for enhancing grapevine production and mitigating the impacts of fungal diseases in viticulture.